<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
    <title>WebGPU Textured Cube Map</title>
    <style>
      @import url(resources/webgpu-lesson.css);
html, body {
  margin: 0;       /* remove the default margin          */
  height: 100%;    /* make the html,body fill the page   */
}
canvas {
  display: block;  /* make the canvas act like a block   */
  width: 100%;     /* make the canvas fill its container */
  height: 100%;
}
    </style>
  </head>
  <body>
    <canvas></canvas>
  </body>
  <script type="module">
// see https://webgpufundamentals.org/webgpu/lessons/webgpu-utils.html#wgpu-matrix
import {mat4} from '../3rdparty/wgpu-matrix.module.js';
import GUI from '../3rdparty/muigui-0.x.module.js';

function generateFace(size, {faceColor, textColor, text}) {
  const canvas = document.createElement('canvas');
  canvas.width = size;
  canvas.height = size;
  const ctx = canvas.getContext('2d');
  ctx.fillStyle = faceColor;
  ctx.fillRect(0, 0, size, size);
  ctx.font = `${size * 0.7}px sans-serif`;
  ctx.fillStyle = textColor;
  ctx.textAlign = 'left';
  ctx.textBaseline = 'top';
  const m = ctx.measureText(text);
  ctx.fillText(
    text,
    (size - m.actualBoundingBoxRight + m.actualBoundingBoxLeft) / 2,
    (size - m.actualBoundingBoxDescent + m.actualBoundingBoxAscent) / 2
  );
  return canvas;
}

const faceSize = 128;
const faceCanvases = [
  { faceColor: '#F00', textColor: '#0FF', text: '+X' },
  { faceColor: '#FF0', textColor: '#00F', text: '-X' },
  { faceColor: '#0F0', textColor: '#F0F', text: '+Y' },
  { faceColor: '#0FF', textColor: '#F00', text: '-Y' },
  { faceColor: '#00F', textColor: '#FF0', text: '+Z' },
  { faceColor: '#F0F', textColor: '#0F0', text: '-Z' },
].map(faceInfo => generateFace(faceSize, faceInfo));

function createCubeVertices() {
  const vertexData = new Float32Array([
     // front face
    -1,  1,  1,
    -1, -1,  1,
     1,  1,  1,
     1, -1,  1,
     // right face
     1,  1, -1,
     1,  1,  1,
     1, -1, -1,
     1, -1,  1,
     // back face
     1,  1, -1,
     1, -1, -1,
    -1,  1, -1,
    -1, -1, -1,
    // left face
    -1,  1,  1,
    -1,  1, -1,
    -1, -1,  1,
    -1, -1, -1,
    // bottom face
     1, -1,  1,
    -1, -1,  1,
     1, -1, -1,
    -1, -1, -1,
    // top face
    -1,  1,  1,
     1,  1,  1,
    -1,  1, -1,
     1,  1, -1,
  ]);

  const indexData = new Uint16Array([
     0,  1,  2,  2,  1,  3,  // front
     4,  5,  6,  6,  5,  7,  // right
     8,  9, 10, 10,  9, 11,  // back
    12, 13, 14, 14, 13, 15,  // left
    16, 17, 18, 18, 17, 19,  // bottom
    20, 21, 22, 22, 21, 23,  // top
  ]);

  return {
    vertexData,
    indexData,
    numVertices: indexData.length,
  };
}

async function main() {
  const adapter = await navigator.gpu?.requestAdapter();
  const device = await adapter?.requestDevice();
  if (!device) {
    fail('need a browser that supports WebGPU');
    return;
  }

  // Get a WebGPU context from the canvas and configure it
  const canvas = document.querySelector('canvas');
  const context = canvas.getContext('webgpu');
  const presentationFormat = navigator.gpu.getPreferredCanvasFormat();
  context.configure({
    device,
    format: presentationFormat,
    alphaMode: 'premultiplied',
  });

  const module = device.createShaderModule({
    code: /* wgsl */ `
      struct Uniforms {
        matrix: mat4x4f,
      };

      struct Vertex {
        @location(0) position: vec4f,
      };

      struct VSOutput {
        @builtin(position) position: vec4f,
        @location(0) normal: vec3f,
      };

      @group(0) @binding(0) var<uniform> uni: Uniforms;
      @group(0) @binding(1) var ourSampler: sampler;
      @group(0) @binding(2) var ourTexture: texture_cube<f32>;

      @vertex fn vs(vert: Vertex) -> VSOutput {
        var vsOut: VSOutput;
        vsOut.position = uni.matrix * vert.position;
        vsOut.normal = normalize(vert.position.xyz);
        return vsOut;
      }

      @fragment fn fs(vsOut: VSOutput) -> @location(0) vec4f {
        return textureSample(ourTexture, ourSampler, normalize(vsOut.normal));
      }
    `,
  });

  const pipeline = device.createRenderPipeline({
    label: '1 attribute',
    layout: 'auto',
    vertex: {
      module,
      buffers: [
        {
          arrayStride: (3) * 4, // (3) floats 4 bytes each
          attributes: [
            {shaderLocation: 0, offset: 0, format: 'float32x3'},  // position
          ],
        },
      ],
    },
    fragment: {
      module,
      targets: [{ format: presentationFormat }],
    },
    primitive: {
      cullMode: 'back',
    },
    depthStencil: {
      depthWriteEnabled: true,
      depthCompare: 'less',
      format: 'depth24plus',
    },
  });

  const numMipLevels = (...sizes) => {
    const maxSize = Math.max(...sizes);
    return 1 + Math.log2(maxSize) | 0;
  };

  function copySourcesToTexture(device, texture, sources, {flipY} = {}) {
    sources.forEach((source, layer) => {
      device.queue.copyExternalImageToTexture(
        { source, flipY, },
        { texture, origin: [0, 0, layer] },
        { width: source.width, height: source.height },
      );
    });
    if (texture.mipLevelCount > 1) {
      generateMips(device, texture);
    }
  }

  function createTextureFromSources(device, sources, options = {}) {
    // Assume are sources all the same size so just use the first one for width and height
    const source = sources[0];
    const texture = device.createTexture({
      format: 'rgba8unorm',
      mipLevelCount: options.mips ? numMipLevels(source.width, source.height) : 1,
      size: [source.width, source.height, sources.length],
      usage: GPUTextureUsage.TEXTURE_BINDING |
             GPUTextureUsage.COPY_DST |
             GPUTextureUsage.RENDER_ATTACHMENT,
    });
    copySourcesToTexture(device, texture, sources, options);
    return texture;
  }

  const generateMips = (() => {
    let sampler;
    let module;
    const pipelineByFormat = {};

    return function generateMips(device, texture) {
      if (!module) {
        module = device.createShaderModule({
          label: 'textured quad shaders for mip level generation',
          code: /* wgsl */ `
            struct VSOutput {
              @builtin(position) position: vec4f,
              @location(0) texcoord: vec2f,
            };

            @vertex fn vs(
              @builtin(vertex_index) vertexIndex : u32
            ) -> VSOutput {
              let pos = array(

                vec2f( 0.0,  0.0),  // center
                vec2f( 1.0,  0.0),  // right, center
                vec2f( 0.0,  1.0),  // center, top

                // 2st triangle
                vec2f( 0.0,  1.0),  // center, top
                vec2f( 1.0,  0.0),  // right, center
                vec2f( 1.0,  1.0),  // right, top
              );

              var vsOutput: VSOutput;
              let xy = pos[vertexIndex];
              vsOutput.position = vec4f(xy * 2.0 - 1.0, 0.0, 1.0);
              vsOutput.texcoord = vec2f(xy.x, 1.0 - xy.y);
              return vsOutput;
            }

            @group(0) @binding(0) var ourSampler: sampler;
            @group(0) @binding(1) var ourTexture: texture_2d<f32>;

            @fragment fn fs(fsInput: VSOutput) -> @location(0) vec4f {
              return textureSample(ourTexture, ourSampler, fsInput.texcoord);
            }
          `,
        });

        sampler = device.createSampler({
          minFilter: 'linear',
          magFilter: 'linear',
        });
      }

      if (!pipelineByFormat[texture.format]) {
        pipelineByFormat[texture.format] = device.createRenderPipeline({
          label: 'mip level generator pipeline',
          layout: 'auto',
          vertex: {
            module,
          },
          fragment: {
            module,
            targets: [{ format: texture.format }],
          },
        });
      }
      const pipeline = pipelineByFormat[texture.format];

      const encoder = device.createCommandEncoder({
        label: 'mip gen encoder',
      });

      for (let baseMipLevel = 1; baseMipLevel < texture.mipLevelCount; ++baseMipLevel) {
        for (let layer = 0; layer < texture.depthOrArrayLayers; ++layer) {
          const bindGroup = device.createBindGroup({
            layout: pipeline.getBindGroupLayout(0),
            entries: [
              { binding: 0, resource: sampler },
              {
                binding: 1,
                resource: texture.createView({
                  dimension: '2d',
                  baseMipLevel: baseMipLevel - 1,
                  mipLevelCount: 1,
                  baseArrayLayer: layer,
                  arrayLayerCount: 1,
                }),
              },
            ],
          });

          const renderPassDescriptor = {
            label: 'our basic canvas renderPass',
            colorAttachments: [
              {
                view: texture.createView({
                  dimension: '2d',
                  baseMipLevel: baseMipLevel,
                  mipLevelCount: 1,
                  baseArrayLayer: layer,
                  arrayLayerCount: 1,
                }),
                loadOp: 'clear',
                storeOp: 'store',
              },
            ],
          };

          const pass = encoder.beginRenderPass(renderPassDescriptor);
          pass.setPipeline(pipeline);
          pass.setBindGroup(0, bindGroup);
          pass.draw(6);  // call our vertex shader 6 times
          pass.end();
        }
      }

      const commandBuffer = encoder.finish();
      device.queue.submit([commandBuffer]);
    };
  })();

  const texture = await createTextureFromSources(
      device, faceCanvases, {mips: true, flipY: false});

  const sampler = device.createSampler({
    magFilter: 'linear',
    minFilter: 'linear',
    mipmapFilter: 'linear',
  });

  // matrix
  const uniformBufferSize = (16) * 4;
  const uniformBuffer = device.createBuffer({
    label: 'uniforms',
    size: uniformBufferSize,
    usage: GPUBufferUsage.UNIFORM | GPUBufferUsage.COPY_DST,
  });

  const uniformValues = new Float32Array(uniformBufferSize / 4);

  // offsets to the various uniform values in float32 indices
  const kMatrixOffset = 0;

  const matrixValue = uniformValues.subarray(kMatrixOffset, kMatrixOffset + 16);

  const { vertexData, indexData, numVertices } = createCubeVertices();
  const vertexBuffer = device.createBuffer({
    label: 'vertex buffer vertices',
    size: vertexData.byteLength,
    usage: GPUBufferUsage.VERTEX | GPUBufferUsage.COPY_DST,
  });
  device.queue.writeBuffer(vertexBuffer, 0, vertexData);

  const indexBuffer = device.createBuffer({
    label: 'index buffer',
    size: vertexData.byteLength,
    usage: GPUBufferUsage.INDEX | GPUBufferUsage.COPY_DST,
  });
  device.queue.writeBuffer(indexBuffer, 0, indexData);

  const bindGroup = device.createBindGroup({
    label: 'bind group for object',
    layout: pipeline.getBindGroupLayout(0),
    entries: [
      { binding: 0, resource: { buffer: uniformBuffer }},
      { binding: 1, resource: sampler },
      { binding: 2, resource: texture.createView({dimension: 'cube'}) },
    ],
  });

  const renderPassDescriptor = {
    label: 'our basic canvas renderPass',
    colorAttachments: [
      {
        // view: <- to be filled out when we render
        loadOp: 'clear',
        storeOp: 'store',
      },
    ],
    depthStencilAttachment: {
      // view: <- to be filled out when we render
      depthClearValue: 1.0,
      depthLoadOp: 'clear',
      depthStoreOp: 'store',
    },
  };

  const degToRad = d => d * Math.PI / 180;

  const settings = {
    rotation: [degToRad(20), degToRad(25), degToRad(0)],
  };

  const radToDegOptions = { min: -360, max: 360, step: 1, converters: GUI.converters.radToDeg };

  const gui = new GUI();
  gui.onChange(render);
  gui.add(settings.rotation, '0', radToDegOptions).name('rotation.x');
  gui.add(settings.rotation, '1', radToDegOptions).name('rotation.y');
  gui.add(settings.rotation, '2', radToDegOptions).name('rotation.z');

  let depthTexture;

  function render() {
    // Get the current texture from the canvas context and
    // set it as the texture to render to.
    const canvasTexture = context.getCurrentTexture();
    renderPassDescriptor.colorAttachments[0].view = canvasTexture.createView();

    // If we don't have a depth texture OR if its size is different
    // from the canvasTexture when make a new depth texture
    if (!depthTexture ||
        depthTexture.width !== canvasTexture.width ||
        depthTexture.height !== canvasTexture.height) {
      if (depthTexture) {
        depthTexture.destroy();
      }
      depthTexture = device.createTexture({
        size: [canvasTexture.width, canvasTexture.height],
        format: 'depth24plus',
        usage: GPUTextureUsage.RENDER_ATTACHMENT,
      });
    }
    renderPassDescriptor.depthStencilAttachment.view = depthTexture.createView();

    const encoder = device.createCommandEncoder();
    const pass = encoder.beginRenderPass(renderPassDescriptor);
    pass.setPipeline(pipeline);
    pass.setVertexBuffer(0, vertexBuffer);
    pass.setIndexBuffer(indexBuffer, 'uint16');

    const aspect = canvas.clientWidth / canvas.clientHeight;
    mat4.perspective(
        60 * Math.PI / 180,
        aspect,
        0.1,      // zNear
        10,      // zFar
        matrixValue,
    );
    const view = mat4.lookAt(
      [0, 1, 5],  // camera position
      [0, 0, 0],  // target
      [0, 1, 0],  // up
    );
    mat4.multiply(matrixValue, view, matrixValue);
    mat4.rotateX(matrixValue, settings.rotation[0], matrixValue);
    mat4.rotateY(matrixValue, settings.rotation[1], matrixValue);
    mat4.rotateZ(matrixValue, settings.rotation[2], matrixValue);

    // upload the uniform values to the uniform buffer
    device.queue.writeBuffer(uniformBuffer, 0, uniformValues);
    pass.setBindGroup(0, bindGroup);
    pass.drawIndexed(numVertices);

    pass.end();

    const commandBuffer = encoder.finish();
    device.queue.submit([commandBuffer]);
  }

  const observer = new ResizeObserver(entries => {
    for (const entry of entries) {
      const canvas = entry.target;
      const width = entry.contentBoxSize[0].inlineSize;
      const height = entry.contentBoxSize[0].blockSize;
      canvas.width = Math.max(1, Math.min(width, device.limits.maxTextureDimension2D));
      canvas.height = Math.max(1, Math.min(height, device.limits.maxTextureDimension2D));
      // re-render
      render();
    }
  });
  observer.observe(canvas);
}

function fail(msg) {
  alert(msg);
}

main();
  </script>
</html>
